Rhododendron plant named ‘QBACKB’

ABSTRACT

A new and distinct  Rhododendron  cultivar named ‘QBackB’ is disclosed, characterized by distinctive large, fragrant, yellow-orange flowers with orange-red flushing. Plants are deciduous, tolerant of heat and humidity, tolerant of mildew and begin blooming before foliage emerges. The new cultivar is a  Rhododendron , suitable for ornamental garden purposes.

Latin name of the genus and species: Rhododendron hybrid.

Variety denomination: ‘QBackB’.

BACKGROUND OF THE INVENTION

The new cultivar is a product of a planned breeding program by theinventor, Robert Edward Lee. The inventor's intention was to developRhododendron hybrid plants with tolerance for heat and humidity andfragrant flowers with vibrant colors. This new variety, hereinafterreferred to as ‘QBACKB’, was discovered as a seedling, resulting fromthe crossing of an unnamed, unpatented proprietary seedling, resultingfrom the open pollination of Rhododendron austrinum with Rhododendronhybrid ‘Gibraltar’ with the pollen parent, Rhododendron hybrid‘Chectco’, unpatented. The cross was performed during the Spring of1984, and the new variety selected by the inventor during Spring of 1990in Folsom, La.

After identifying the new variety as a potentially interestingselection, the inventor first propagated ‘QBACKB’ by vegetative softwoodcuttings during late Spring of 1990 at a commercial nursery in Folsom,La. The inventor continued confidential and controlled testing andpropagation, assessing stability of the unique characteristics of thisvariety. Multiple generations have been reproduced and have shown thatthe unique features of this cultivar are stable and reproduced true totype.

SUMMARY OF THE INVENTION

The cultivar ‘QBACKB’ has not been observed under all possibleenvironmental conditions. The phenotype may vary somewhat withvariations in environment such as temperature, day length, and lightintensity, without, however, any variance in genotype. The followingtraits have been repeatedly observed and are determined to be the uniquecharacteristics of ‘QBACKB’ These characteristics in combinationdistinguish ‘QBACKB’ as a new and distinct Rhododendron cultivar:

-   -   1. Vibrant yellow-orange flowers flushed with red-orange.    -   2. Plant naturally forms a small tree to a large bush form, with        maturity 4 to 6 feet wide and 6 to 8 feet tall, and tolerates        pruning to a smaller size.    -   3. Fragrant flowers    -   4. Manageable growth habit    -   5. Large bloom size    -   6. Large bloom truss    -   7. Blooms open before foliage appears in established landscape        planning    -   8. Heat and humidity tolerant    -   9. Increased tolerance to Erysiphe azaleae

COMPARISON TO PARENT VARIETY

‘QBACKB’ is similar in most horticultural characteristics to the unnamedseed parent variety. Plants of the new cultivar ‘QBACKB’ however,produce larger flowers, and begin blooming later than the seed parent.Additionally, plant habit is overall more manageable and better suitedto landscape situation than the seed parent.

‘QBACKB’ is similar in most horticultural characteristics to the pollenparent Rhododendron hybrid ‘Chectco’. Plants of the new cultivar‘QBACKB’ however, differ in the following characteristics:

-   -   1. More heat tolerant than pollen parent.    -   2. Slightly smaller flower size than pollen parent.    -   3. More mildew resistance than pollen parent.    -   4. Earlier blooming time than pollen parent.    -   5. More manageable and attractive growth habit than the pollen        parent.

COMMERCIAL COMPARISON

‘QBACKB’ can be compared to the commercial variety Rhododendron hybrid‘Admiral Semmes’ unpatented. Plants of the new cultivar ‘QBACKB’ aresimilar to plants of ‘Admiral Semmes’ in most horticulturalcharacteristics, however, plants of the new cultivar ‘QBACKB’ differ inthe following characteristics:

-   -   1. More vibrant flower color of the new variety, with flushes of        red and orange-red.    -   2. The new variety begins blooming earlier than ‘Admiral        Semmes’(.)    -   3. ‘QBACKB’ reaches a mature height of 6 to 8 feet, ‘Admiral        Semmes’ reaches a mature height of approximately 4 to 5 feet.

‘QBACKB’ can be compared to the commercial variety Rhododendron hybrid‘QBackA’, Plant patent application Ser. No. 14/120,168. Plants of thenew cultivar ‘QBACKB’ are similar to plants of ‘QBackA’ in mosthorticultural characteristics, however, plants of the new cultivar‘QBACKB’ differ in the following characteristics:

-   -   1. ‘QBACKB’ has yellow-orange flowers with orange-red flush,        whereas ‘QBackA’ has orange flowers, streaked with orange-red.    -   2. ‘QBACKB’ begins blooming approximately 2 weeks later than        ‘QBackA’.    -   3. ‘QBACKB’ reaches a mature height of 6 to 8 feet, ‘QBackA’        reaches a mature height of approximately 8 to 10 feet.

BRIEF DESCRIPTION OF THE PHOTOGRAPHS

The accompanying photograph in FIG. 1 illustrates in full color atypical plant of ‘QBACKB’, of approximately 2 years old.

FIG. 2 illustrates a close up of typical flowers of the new variety.

The photographs were taken using conventional techniques and althoughcolors may appear different from actual colors due to light reflectanceit is as accurate as possible by conventional photographic techniques.

DETAILED BOTANICAL DESCRIPTION

In the following description, color references are made to The RoyalHorticultural Society Colour Chart 2007 except where general terms ofordinary dictionary significance are used. The following observationsand measurements describe ‘QBACKB’ plants grown outdoors in Loxley, Ala.Plants are approximately 2 years old, in a 2 gallon nursery container.Measurements and numerical values represent averages of typical planttypes.

-   Botanical classification: Rhododendron hybrid ‘QBACKB’.

PROPAGATION

-   Typically by semi-hardwood cuttings in Spring and Summer.-   Root description: Fine, fibrous young roots, well branched. Colored    near RHS Grey-Brown N199A.-   Time (approximate days) to initiate roots: 30 to 60 days at 70 to 80    degrees F. day temperatures and 55 to 65 degrees F. night    temperatures.-   Time (approximate days) to produce a rooted plant: Approximately    150-210 days at 70 to 80 degrees F. day temperatures and 55 to 65    degrees F. night temperatures.

PLANT

-   Growth habit: Upright, deciduous woody shrub.-   Height: Approximately 45 cm to top of foliar and flowering plane.-   Plant spread: Approximately 22 cm.-   Branching characteristics: Average 4 to 10 primary branches from the    center of the plant, after giving a low pinch, near soil line.    Branches occur at approximately 15° to 25° angles. Each primary    branch has an average of 2 to 4 lateral branches.-   Primary branches:    -   -   Length of primary branches.—Average 8 cm to 20 cm, then            splits into lateral branches.        -   Diameter of primary branches.—Approximately 0.7 cm.        -   Primary branch strength.—Very strong, difficult to break.        -   Primary branch color.—Near RHS Grey-Brown 199B.        -   Primary branch texture.—Young growth pubescent to nearly            hirsute. Hairs, approximately 0.15 cm long, colored near            Yellow-Green 145B. Older growth moderately scaly and            hirsute.        -   Lateral branches.—Number of Lateral Branches: Average 2 to 4            per primary branch. Length of Lateral Branches: Average 4 cm            to 8 cm, then splits into more branches. Diameter of Lateral            Branches: Average 0.4 cm. Lateral Branch Strength: Very            strong, not flexible, difficult to break. Lateral Branch            Color: Near RHS Grey-Brown N199B. Lateral Branch texture:            Scaly, hirsute.        -   Internode length.—Average 5 cm.        -   Age of plant described.—Approximately 2 years.

FOLIAGE

-   Leaf:    -   -   Type.—Simple.        -   Arrangement.—Leaves occur in a whorl at the end of branches.            Foliage emerges after flowering begins.        -   Average length.—Approximately 5.9 cm.        -   Average width.—Approximately 2.4 cm.        -   Shape of blade.—Elliptic.        -   Apex.—Acute to slightly mucronate.        -   Base.—Attenuate.        -   Attachment.—Sessile.        -   Margin.—Entire.        -   Texture of top surface.—Pubescent. Hairs appressed.        -   Texture of bottom surface.—Faintly pubescent. More hairs            present along main vein and margin.        -   Appearance of top surface.—Matte, not glossy.        -   Appearance of bottom surface.—Matte, not glossy.        -   Color.—Young foliage upper side: Near RHS Yellow-Green 144A.            Mucronate apex near Greyed-Purple 183A. Faint flush on apex            near Greyed-Purple 183A. Young foliage under side: Near RHS            Yellow-Green 144B. Mature foliage upper side: Near RHS            Yellow-Green 144A, faintly flushed Greyed-Orange 175A.            Mature foliage under side: Near RHS Green 138B.        -   Venation.—Type: Pinnate. Underside of leaf veins prominently            raised. Venation color upper side: Near RHS Yellow-Green            153D. Venation color under side: Near RHS Yellow-Green 153B.

FLOWER

-   Bloom period: Plants flower in the Spring, around late April, with a    2 to 3 week flowering period. Flowering again during the same year    has not been observed.-   Flower:    -   -   Arrangement.—Axillary clusters of single, perfect, open            funnel shaped individual flowers. Typically 5 open flowers            and 5 buds per cluster.-   Inflorescence:    -   -   Height.—Average 9.0 cm.        -   Diameter.—Average 15.0 cm.        -   Overall shape.—Globular.-   Peduncle: No true peduncle, flower cluster emerges directly from    lateral woody stem.-   Pedicel:    -   -   Length.—Average 1.3 cm.        -   Diameter.—0.25 cm.        -   Color.—Near RHS Yellow-Green 144B, slightly flushed with            Greyed-Red 180A near flower attachment.        -   Texture.—Densely pubescent.        -   Aspect.—Straight. Angle of attachment, approximately 75°            angle from stem, outermost flowers.        -   Strength.—Strong and flexible.-   Flowers:    -   -   Length.—Average 5.4 cm.        -   Diameter.—Average 7.2 cm.        -   Facing direction.—Outwardly and upwardly facing.        -   Persistent or self-cleaning.—Petals self-cleaning.        -   Fragrance.—Very strong sweet fragrance.        -   Tube.—Tube length: Approximately 2.4 cm. Tube width a widest            point: Approximately 1.1 cm. Tube width and narrowest point:            Approximately 0.6 cm.        -   Color.—Inner surface at first opening: Near RHS            Yellow-Orange 14C. Outer surface at first opening: Near RHS            Yellow-Orange 14C, and heavily flushed Yellow-Orange 14A.            Inner surface at maturity: Near RHS Yellow-Orange 14C.            Flushed Orange-Red 34C. Outer surface at maturity: Near RHS            Yellow-Orange 14C. Small streaks of Orange-Red 34A. Inner            surface at fading: Near RHS Yellow-Orange 14D. Outer surface            at fading: Near RHS Yellow-Orange 18A. Large streaks of            Orange-Red 34A.        -   Petals.—Unfused petal segments: Length: Approximately            3.4 cm. Width: Approximately 2.07 cm. Apex: Ruffled. Shape            of petal: Unfused portion, obovate. Petal margin: Ruffled.            Petal Arrangement: Approximately ⅓ fused from base. Unfused            section overlapping. Petal Number: 5. Petal Texture: Smooth,            all surfaces.        -   Color.—Inner surface at first opening: Near RHS            Yellow-Orange 14C. Flushed Orange-Red 34C. Outer surface at            first opening: Near RHS Yellow-Orange 14D. Flushed            Orange-Red 34C. Inner surface at maturity: Near RHS            Yellow-Orange 14C. Flushed Orange-Red N34C. Outer surface at            maturity: Near RHS Yellow-Orange 15D. Flushed Red 39A. Inner            surface at fading: Near RHS Yellow-Orange 14D. Flushed Red            39A. Outer surface at fading: Near RHS Yellow-Orange 14D.            Flushed Red 39A.-   Bud:    -   -   Shape.—Elliptic, with inflated apical end.        -   Length.—5.4 cm.        -   Diameter.—2.0 cm at widest point.        -   Color.—Near RHS Yellow-Orange 14C. Flushed Orange-Red N34C            at distal end.-   Calyx/sepals:    -   -   Quantity per flower.—5 sepals.        -   Shape.—Deltate.        -   Length.—0.3 cm.        -   Width.—0.2 cm.        -   Apex.—Acute.        -   Base.—Fused.        -   Margin.—Entire.        -   Texture.—Highly pubescent inner and outer surfaces. Color:            Inner Surface: Near RHS Green 138B. Outer Surface: Near RHS            Green 138B.-   Floral bracts:    -   -   Shape.—Deltate.        -   Length.—1.5 cm.        -   Diameter.—0.7 cm at widest point.        -   Color.—Near RHS Yellow 10B, flushed Greyed-Purple 183B at            base, Greyed-Purple 187A at apex, upper and lower surfaces.        -   Texture.—Pubescent.

REPRODUCTIVE ORGANS

-   Stamens:    -   -   Number.—5.        -   Length.—8.2 cm.        -   Width.—0.15 cm.        -   Color.—Near RHS Yellow-Orange 14D.        -   Anthers.—Length: Approximately 0.4 cm. Diameter:            Approximately 0.2 cm. Shape: Linear. Color: Near RHS            Yellow-Orange 14D, small flush near Orange-Red 34C. Pollen:            Moderate, colored near Greyed-Orange 163D.-   Pistil:    -   -   Number.—1.        -   Length.—9.1 cm.        -   Style.—Length: 8.5 cm. Color: Near RHS Yellow-Orange 22B.        -   Stigma.—Globular, colored near Yellow-Green 146A.        -   Ovary.—Sericeous texture. Approximately 0.2 cm in diameter.            Colored near Green 137A.

OTHER CHARACTERISTICS

-   Disease and pest resistance: Not observed to be susceptible nor    resistant to normal pests of Rhododendron hybrid. Increased    tolerance to mildew Erysiphe azalea.-   Temperature tolerance: USDA Zone 6.-   Fruit/seed production: Not observed to date.

What is claimed is:
 1. A new and distinct cultivar of Rhododendron plantnamed ‘QBACKB’ as herein illustrated and described.